A team of researchers led by scientists from UC Irvine discovered that the underlying cause for the melting was accelerated glacier flow, which is, in turn, caused by warming oceans. All that melting means higher sea levels:

They detected a sharp jump in Antarctica's ice loss, from enough ice to raise global sea level by 0.3 millimeters (.01 inches) a year in 1996, to 0.5 millimeters (.02 inches) a year in 2006.

That level of melting puts western Antarctica almost on par with Greenland, a dubious distinction, to say the very least.